Method of removing coating film

ABSTRACT

The present invention provides a method of removing a coating film from the surface of a coated product, which method includes supplying an abrasive onto the surface of a coating film, pressing the abrasive to the surface of a coating film with a press surface of a press element to crush the coating film into a crushed coating film, and removing the abrasive and the crushed coating film, and a method of removing a coating film from the surface of a coated product using a jig for pressing an abrasive onto a coating film with a press element, and crushing the coating film, wherein the jig contains a jig base and plural press elements, and the press element is connected to the jig base such that the press element can be at least displaced to elastically approach or leave the jig base.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a method of removing a coating film formed on the surface of a coated product such as floor materials.

BACKGROUND OF THE INVENTION

[0002] As a method of removing a coating film formed on the surface of a coated product, there are conventionally known many methods of physically removing a coating film, such as a method including scraping a coating film using an abrasive paper or a grinder, a method including application of an impact to remove a coating film by shooting a powder, such as sand, at a high speed against the film (sandblast method), a method including striking a coating film with a hammer to remove the film and the like.

[0003] However, the method using an abrasive paper or a grinder to scrape a coating film frequently damages a coated product when the thickness of the film is inconsistent and the surface of the coated product is uneven, because this method scrapes the coated product along with the film. When the coating film is scraped by a small portion in order not to damage the coated product, the time necessary for completely removing the coating film becomes quite long.

[0004] When the sandblast method is used to remove a film on a coated product made from plastic, wood and the like, the impact often leaves strike marks and flaws on the coated product. By this sandblast method, again, when the coating film is struck by a small amount in order not to damage the coated product, the time necessary for completely removing the coating film becomes considerably long.

[0005] The method including striking a coating film with a hammer to remove the film is used to remove a coating film accumulated on a jig for coating, but this method often causes deformation of the coated product.

[0006] As a method of chemically removing a coating film, a method of decomposing and dissolving a coating film by the use of a peeling agent is known. For complete removal of a coating film, however, a strong peeling agent needs to be used and when the coated product is made of plastic, wood, marble and the like, it easily causes swelling or dissolution of the coated product.

SUMMARY OF THE INVENTION

[0007] The present invention has been made to solve the above-mentioned problems, and aims at providing a method of removing a coating film easily in a short time while suppressing damage and degradation of the coated product, and further a method capable of crushing the coating film by pressing an abrasive against a surface of the coating film almost uniformly even if the surface of the coating film has irregularities and windings.

[0008] Accordingly, the present invention provides the following.

[0009] (1) A method of removing a coating film from the surface of a coated product, which method comprises

[0010] supplying an abrasive onto the surface of a coating film,

[0011] pressing the abrasive against the surface of the coating

[0012] film with a press surface of a press element to convert

[0013] the coating film into a crushed coating film, and

[0014] removing the abrasive and the crushed coating film.

[0015] (2) The method of (1) above, which further comprises applying a peeling agent onto a surface of the crushed coating film.

[0016] (3) The method of (2) above, wherein the peeling agent dissolves at least a lowermost layer of the coating film.

[0017] (4) The method of (1) above, wherein the press surface of the press element is curved.

[0018] (5) The method of (1) above, wherein the press element is a free turning roller.

[0019] (6) The method of (5) above, wherein the turning roller is attached to a rotary seat of a rotary driven type.

[0020] (7) The method of (1) above, wherein the press surface of a press element has a curve winding in the direction of movement.

[0021] (8) The method of (1) above, wherein the abrasive is pressed plural times against the surface of a coating film with the press surface of a press element.

[0022] (9) The method of (1) above, wherein the coated product is a floor material.

[0023] (10) A method of removing a coating film from the surface of a coated product by the use of a jig for pressing an abrasive onto a coating film with a press element to crush the coating film, wherein the jig comprises a jig base and plural press elements, and the press elements are connected to a jig base such that each press element can be at least displaced to elastically approach or leave the jig base.

[0024] (11) The method of (10) above, wherein the aforementioned jig base has plural through holes, and each press element is connected to the jig base via plural shafts inserted into each through hole in such a manner that they can at least reciprocate in the through holes.

[0025] (12) The method of (10) above, wherein the press element is connected to the jig base such that the press element can be at least displaced to elastically approach or leave the jig base and an end thereof is capable of elastic angular displacement relative to the jig base.

[0026] (13) The method of (12) above, wherein the aforementioned jig base has plural through holes, and each press element is connected to the jig base via plural shafts inserted into each through hole in such a manner that they are capable of reciprocation and angular displacement in the through hole.

[0027] (14) The method of (10) above, further comprising an elastic member between the jig base and the press element.

[0028] (15) The method of (10) above, wherein the press element is a column having a curved end forming a protrusion toward the direction away from the jig base.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1(a) to FIG. 1(c) show a method of removing a coating film of Example 1.

[0030]FIG. 2(d) to FIG. 2(g) follow FIG. 1(a) to FIG. 1(c) and show the method of removing a coating film of Example 1.

[0031]FIG. 3 is a perspective view of a press element used for the method of removing a coating film of Example 1.

[0032]FIG. 4(a) is a plan view of an apparatus equipped with a jig for crushing a coating film used for a method of removing a coating film in Example 2 and FIG. 4(b) is a plan view of a seat mounting part of the apparatus of FIG. 4(a).

[0033]FIG. 5 includes a plan view (a) and a side view (b) of a rotary seat of the apparatus of FIG. 4(a).

[0034]FIG. 6 is a simplified front view of a jig 21 for crushing a coating film of one preferable embodiment of the present invention, wherein hatching in the Figure is used for demarcation purposes.

[0035]FIG. 7 is a top view of a jig 21 for crushing a coating film shown in FIG. 6.

[0036]FIG. 8 is a side view of a jig 21 for crushing a coating film shown in FIG. 6, wherein hatching in the Figure is used for demarcation purposes.

[0037]FIG. 9(a) is a sectional view of the side view of jig 21 shown in FIG. 8 wherein section IV is enlarged, and FIG. 9(b) is a sectional view wherein a press element 23 is displaced toward a jig base 22 from the state shown in FIG. 9(a).

[0038]FIG. 10(a) is a sectional view of the front view of jig 21 shown in FIG. 6, wherein section V is enlarged, and FIG. 10(b) is a sectional view of a tip 23 a of a press element 23 after angular displacement relative to jig base 22 from the state shown in FIG. 10(a).

DETAILED DESCRIPTION OF THE INVENTION

[0039] The present invention provides a method of removing a coating film from the surface of a coated product, which method comprises supplying an abrasive onto the surface of a coating film, pressing the abrasive against the surface of a coating film with a press surface of a press element to crush the coating film into a crushed coating film, and removing the abrasive and the crushed coating film.

[0040] According to the method of removing a coating film of the present invention, an abrasive is supplied onto the surface of a coating film and the abrasive is pressed with a press element. By pressing the abrasive, the coating film is crushed generally in several seconds and becomes a crushed coating film containing crushed pieces of the coating film. The crushed pieces can be removed easily in a short time by suction and the like.

[0041] While the coating film is crushed by merely pressing an abrasive, the coated product underneath is hardly damaged. Since a coating film is crushed by a physical action, a coated product is free of degradation, such as deformation, swelling, dissolution, decomposition and the like, when removing the coating film.

[0042] According to the present invention, a coating film can be removed easily in a short time while suppressing damage to the coated product.

[0043] The method of removing a coating film of the present invention preferably includes a further step for applying a peeling agent to the surface of the above-mentioned crushed coating film. By this step, a coating film is dissolved in a peeling agent, and the adhesion between the coating film and the surface of a coated product is remarkably decreased. As a result, the coating film can be removed more easily. In this case, the crushed coating film is more preferable than a non-crushed coating film. This is because the contact area with the peeling agent increases when a coating film is crushed, and the peeling agent works more effectively.

[0044] The peeling agent to be used in the present invention is a chemical employed with the aim of removing the coating film by application to a coating film.

[0045] The peeling agent should not cause deformation, swelling, dissolution, decomposition and the like of a coated product. Examples of the peeling agent include peeling agents for coating films, peeling agents for wax, materials described in JP-B-7-78240, JP-B-6-70201, JP-B-6-33429, JP-A-9-132739 and JP-A-9-241687, for which the methods disclosed therein can be used.

[0046] The peeling agent may be an organic solvent-based peeling agent or a water-based peeling agent in any form. When it is used at an operation site, a water-based peeling agent is preferable because it gives fewer odors and is free from danger of catching fire.

[0047] According to the method of removing a coating film of the present invention, at least the lowermost layer of the above-mentioned coating film preferably dissolves in the above-mentioned peeling agent. The uppermost layer of the coating film is crushed by the above-mentioned abrasive, thereby exposing the lowermost layer or allowing cracks to reach the surface. As a result, the peeling agent reaches the lowermost layer in a short time and dissolves the coating film, which in turn makes removal of the coating film still easier.

[0048] Whether or not at least the lowermost layer of the coating film dissolves in a peeling agent can be determined by the following method. A coating film to be the lowermost layer is formed onto a smooth and chemically stable substrate such as glass plate and the like. A given peeling agent is spotted and the agent is removed in 30 minutes. When the coating film becomes swollen, softened, or is easily removed along with the peeling agent at this time, it means that at least the lowermost layer of the coating film has been dissolved. When the coating film is without change from that on its formation, such as swelling and softening, and cannot be removed easily, it means that at least the lowermost layer of the coating film has not been dissolved.

[0049] The above-mentioned press element is a jig used to press an abrasive against the surface of a coating film.

[0050] According to the method of removing a coating film of the present invention, the above-mentioned press surface of the above-mentioned press element is preferably curved. When the press surface is planar, uniform pressing of the abrasive against the surface of a coating film cannot be attained, resulting in lower coating film removal efficacy. Particularly when the surface of a coated product has irregularities, this tendency is noticeable. When the press surface is sharp, it may damage the surface of a coated product when the press element is moved. Therefore, the press surface is preferably smooth and curved, as mentioned above.

[0051] According to the method of removing a coating film of the present invention, the above-mentioned press element is preferably a turning roller that rotates freely. As a result, the abrasive digs uniformly into the surface of a coating film irrespective of the irregularities on the surface of a coating film. This prevents occurrence of a damaged coated product upon removal of the coating film. The press element consisting of a turning roller is particularly preferable for a coated product having radical irregularities.

[0052] The turning roller is cylindrical or spherical and permits movement in all directions without difficulty. A turning roller is made from metals such as steel, stainless, brass and the like, ceramic, plastic or rubber. of these, those made of a metal or ceramic are preferable from the aspects of wear and abrasion resistance.

[0053] According to the method of removing a coating film of the present invention, the above-mentioned turning roller is preferably set on a rotary seat (i.e., jig base) of a rotary driven type. This allows an abrasive to uniformly dig into a coating film, thereby further improving the coating film removal efficiency. Therefore, a coating film can be removed easily in a short time without scraping or damaging the protruded parts of a coated product.

[0054] The number of the turning rollers to be fixed on a rotary seat may be any, but it is preferably not less than 3 to afford stable driving of the rotary seat on an abrasive.

[0055] To suppress the vibration during driving, a turning roller may be fixed on a rotary seat via a cushioning such as rubber, plastic, metal and the like.

[0056] According to the method of removing a coating film of the present invention, the press surface of the above-mentioned press element is preferably a curve that winds in the direction of movement. This allows an abrasive to uniformly dig into a coating film, without damaging a coated product.

[0057] According to the method of removing a coating film of the present invention, the above-mentioned abrasive is preferably lo pressed against the surface of a coating film plural times by the press surface of a press element. This allows an abrasive to dig into a coating film sufficiently deeply, which in turn facilitates crushing of the coating film and improves coating film removal efficiency.

[0058] The above-mentioned press element may be moved manually or automatically with the aid of a machine.

[0059] Examples of the above-mentioned abrasive include an abrasive powder, an abrasive paper and the like.

[0060] The above-mentioned abrasive powder consists of particles having relatively high hardness. The particle size (JIS R 6010) is not particularly limited and can be determined according to the thickness of the coating film. The particle size of the abrasive powder is preferably larger than the thickness of the coating film. This increases the power to crush a coating film and increases the coating film removal efficiency. For example, when the thickness of the coating film is 5-30 μm, the particle size of the abrasive powder is preferably P50-400. When it is less than P50, the abrasive powders on the surface of a coating film have an enlarged space between them, where an abrasive powder cannot be pressed against the coating film, which ultimately leads to lower coating film removal efficiency. When it exceeds P400, the particle size becomes smaller and only the surface having a smaller thickness of the coating film is crushed, possibly reducing the coating film removal efficiency.

[0061] The above-mentioned abrasive powder may be an inorganic compound such as a metal compound, ceramic and the like or made from an organic compound such as plastic particles and a powder of pulverized cellulose.

[0062] An abrasive powder suitable for a method of removing a coating film may be a powder of diamond, alumina, corundum, emery, garnet, powder emery, silicon carbide, boron nitride, diatomaceous earth, siliceous sand, silicon oxide, iron oxide, chromium (III) oxide, cerium (IV) oxide and the like. Of these, lo alumina, corundum and siliceous sand are particularly preferable in view of the cost.

[0063] The above-mentioned abrasive paper is paper or cloth adhered with a powder and used for scraping or grinding the surface of a coating film. As such powder, the above-mentioned abrasive powder is often used. Examples of the abrasive paper include those available from KOVAX Corporation, SUMITOMO 3M Limited, NCA BUFFALO, FUJI-TOMBO CO., LTD.

[0064] The above-mentioned coating film is formed by applying a coating solution to a coated product and curing the coating solution. The coating film is made from an organic compound, an inorganic compound or a mixture of these. When the coated product is a floor material, the coating film is formed by applying a paint or a floor-polish and curing the same. The coating film may be a coating agent to be applied to a floor material to afford a resin coated floor material.

[0065] Examples of the paint include polyurethane resin paint, acrylic resin paint, unsaturated polyester resin paint, epoxy resin paint, nitrocellulose lacquer, acrylic lacquer, acrylic silicone resin paint, fluorine-contained resin paint, alcohol varnish and the like. The paint may be an organic solvent-based paint, a solventless paint, a water-based paint, an aqueous emulsion paint, an aqueous dispersion paint and the like. As the above-mentioned organic solvent-based paint, for example, an organic solvent such as ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, mineral spirits and the like can be used.

[0066] The form of the paint may be either a liquid or a powder. It may be a room temperature setting paint, a heat setting paint, a UV curable paint or an EB curable paint.

[0067] A floor-polish may be of a polymer type mainly using a polymer or of a wax type mainly using a wax and the form thereof may be a water-base, an emulsion-base, an oil-base and the like.

[0068] As a coating agent to form a resin coated floor material may be those generally used. Examples thereof include epoxy resin-based, urethane resin-based, acrylic resin-based, MMA resin-based, polyester resin-based coating agent and the like.

[0069] The above-mentioned coated product consists of optional base material and is not particularly limited. A coating film is formed on the surface thereof. The base material may be an organic compound, an inorganic compound or a mixture thereof.

[0070] Examples of the organic compound include plastics such as poly(vinyl chloride), polyethylene, polypropylene, PET, polystyrene, polyurethane, polyester, polycarbonate, ABS resin and the like, wood such as cedar, oak, Japanese hemlock, cork, rubber, Agathis and the like, and plywood thereof and laminated wood.

[0071] Examples of the inorganic compound include metals such as iron, stainless, brass, aluminum and the like, ceramics such as porcelain, pottery and the like, stones such as marble, granite and the like, glass, concrete, plaster and the like.

[0072] Examples of the above-mentioned coated product include building materials such as floor material, wall material and the like and furniture such as table, chair, counter and the like.

[0073] Particularly, according to the method of removing a coating film of the present invention, the above-mentioned coated product is preferably a floor material. Since floor materials have large areas and the surface of a coating film formed on a floor material tends to have marked irregularities and undulation, the effect of the present invention in that a coating film can be removed easily in a short time can be effectively exerted.

[0074] The floor material may be of any shape or state as long as it is generally used for floors. For example, the method of the present invention can be applied to conventionally known floor materials made from i) resin material, ii) wooden material, iii) ceramic material, iv) stone material, v) concrete material and the like.

[0075] i) Floor material made from a resin material:

[0076] Examples of the resin material include vinyl chloride and the like. Examples of the floor material made from this material are vinyl floor tiles such as a composition vinyl floor tile, a homogeneous vinyl floor tile and the like, expanded floor sheets such as a cushion floor and the like, floor sheets such as a woven fabric laminated vinyl floor sheet, nonwoven fabric laminated vinyl floor sheet and the like, natural material floor tiles such as linoleum floor material, cork tile, rubber tile and the like.

[0077] ii) Floor material made from a wooden material:

[0078] Examples of the floor material made from a wooden material include flooring, which is specifically single-layer flooring, composite flooring, flooring board, flooring block, mosaic parquet, soundproof floor, sound insulation double floor, free access floor and the like. iii) Floor material made from a ceramic material:

[0079] Examples of the floor material made from a ceramic material include porcelain tile, pottery tile, pottery block, nonslip tile and the like.

[0080] iv) Floor material made from a stone material:

[0081] Examples of the floor material made from a stone material include marble, granite, terrazzo and the like. Examples of the terrazzo include resin terrazzo, cement terrazzo and the like.

[0082] v) Floor material made from a concrete material:

[0083] Examples of the floor material made from a concrete material include mortar and the like.

[0084] Particularly, in shops, hospitals, houses, offices, gymnasium, the above-mentioned floor materials can be used as they are, but often after forming a coating film by painting and floor-polish. Such maintenance work on floor materials prevents deterioration of floor surface, and improves durability. When, however, a coating film is accumulated on a stained coating film, the stain is pushed into the coating film to the point that washing fails to remove the stain. The method of removing a coating film of the present invention has high efficiency of coating film removal and shows superior effect in the floor maintenance work.

[0085] Particularly, a method of removing a coating film of the present invention shows effect on a coating film that cannot be removed easily with a conventional peeling agent.

[0086] The present invention also provides a method of removing a coating film from the surface of a coated product by the use of a jig for crushing the coating film by pressing an abrasive against the coating film with a press element. This jig is equipped with a jig base and plural press elements, and the press element is connected to the jig base such that the press element can be at least displaced to elastically approach or leave the jig base.

[0087]FIG. 6 is a simplified front view of a jig 21 for crushing a coating film of one preferable embodiment of the present invention, FIG. 7 is a top view of the jig 21 for crushing a coating film shown in FIG. 6, and FIG. 8 is a side view of a jig 21 for crushing a coating film shown in FIG. 6.

[0088] The jig 21 of the present invention basically comprises a jig base 22 and plural press elements 23. The jig 21 presses an abrasive against a coating film by the use of a press element 23 to crush the coating film, which is so designed to connect the press element 23 to the jig base 22 such that the press element can be at least displaced to elastically approach or leave the jig base.

[0089] The jig base 22 is not particularly limited as regards its shape, but a longitudinal shape in one direction is preferable because it allows regular arrangement and connection of plural press elements 23 and a large area of a coating film can be crushed at once. FIG. 6-FIG. 8 show an embodiment wherein the jig base 22 is formed with a planar member having a longitudinal shape in one direction. The material to form the jig base 22 is not particularly limited and may be a metal such as iron, steel, stainless steel, various alloys, aluminum and the like, synthetic resin, wood and the like. Preferred is a material having a great specific gravity, such as iron, steel, stainless steel and the like, because the base 22 applies a load on the press element, the base 22 can be made compact, permitting easy handling, and the like.

[0090] The press element 23 presses the object at an end opposite from the side connected to the jig base 22 (hereinafter this end is sometimes referred to as an end 23 a of the press element 23). The shape of an end 23 a varies depending on the shape of the press element 23, and includes about planar, linear, dot, or a combination of these and the like. The arrangement of the press element 23 to be connected to the jig base 22 is not particularly limited. It is preferable that they are arranged about regularly to protrude from one side of the jig base 22. The number of the press elements 23 is not particularly limited can be determined appropriately according to the size, shape, material and the like of the press element 23. FIG. 6-FIG. 8 show an embodiment wherein 10 press elements 23 are arranged in two rows containing 5 each in staggered intervals from each other, generally along the longitudinal direction of the jig base 22. The material forming the press element 23 is not particularly limited, but metal having high hardness such as iron, steel and the like, ceramic and the like are preferable, by which at least an end 23 a is hardly susceptible to abrasion or deformation.

[0091] The structure of the present invention wherein the press element 23 is connected to the jig base 22 such that the press element can be at least displaced to elastically approach or leave the jig base 22 is not particularly limited, and conventionally known various systems can be employed to achieve this connection.

[0092] The following is a preferable embodiment wherein the aforementioned connection is realized by a simple structure.

[0093]FIG. 9(a) is a sectional view of the side view of jig 21 shown in FIG. 8 wherein section IV is enlarged, and FIG. 9(b) is a sectional view wherein a press element 23 is displaced from the state shown in FIG. 9(a) toward a jig base 22. In the embodiment shown in FIG. 9, the jig base 22 has about parallel plural through holes 24 (in the embodiment of FIG. 6-FIG. 8, 10 holes are arranged in two rows containing 5 each in staggered intervals from each other), and each press element 23 is connected to jig base 22 via plural shafts 25 (in the embodiment of FIG. 6-FIG. 8, 10 shafts) inserted into each through hole 24 in such a manner that they can at least reciprocate in each through hole 24. By connection of press element 23 to jig base 22 via shafts 25, the shafts 25 can reciprocate in each through hole 24 in conjunction with the displacement of the press element 23 to approach or leave the jig base 22, whereby the above-mentioned connection permitting displacement of the press element can be realized. The press element 23 and the shaft 25 may be formed integrally, or separately. FIG. 9 shows an embodiment of integral formation of the press element 23 and the shaft 25.

[0094] In the embodiment shown in FIG. 6-FIG. 9, an elastic member 26 is disposed between, for example, jig base 22 and press element 23. The elastic member 26 may be various conventionally known elastic bodies, such as rubber, sponge, spring and the like. In the embodiment shown in FIG. 6-FIG. 9, the periphery of a protrusion from the jig base 22 of the shaft 25 is covered with an elastic member 26. This affords displacement of press element 23 to elastically approach or leave the jig base 22. When a force to press the press element 23 from the end 23 a side, the elastic member 26 elastically deforms to fill the space between press element 23 and jig base 22, buffers and accepts displacement of press element 23 toward jig base 22 (e.g., displacement from the state shown in FIG. 9(a) to the state shown in FIG. 9(b)). When the above-mentioned force is lifted, displacement of press element 23 to elastically leave the jig base 22 (e.g., displacement from the state shown in FIG. 9(b) to the state shown in FIG. 9(a)) occurs due to an elastic return.

[0095] By reciprocating the jig 21 for crushing a coating film of the present invention equipped with the aforementioned jig base 22 and press element 23 while pressing a coating film with a press element 23, with an abrasive intervened, a coating film can be crushed about uniformly even if it has irregularities and undulation on the surface. To be specific, according to the present invention, when an end 23 a of a press element 23 is pressed against the surface of a coating film, each press element 23 follows the irregularities and undulation of the surface of a coating film according to the shape of the irregularities and undulation of the part pressed by each press element, even when the surface of a coating film has irregularities and undulation, wherein the end 23 a displaces to approach the jig base 22 where protrusions are present and displaces to leave the jig base 22 where recesses are present, whereby the coating film is pressed about uniformly. When the coating film is pressed with a press element 23 after an abrasive is supplied onto the surface of a coating film, as mentioned above, the abrasive is pressed against the surface of a coating film about uniformly following the irregularities and undulation on the surface of a coating film, affording about uniform crushing of the coating film. It is needless to say that the jig 21 for crushing a coating film of the present invention can also uniformly crush coating films having an about planar surface.

[0096] In the present invention, a coating film having any surface shape can be crushed about uniformly to remove the coating film at an about uniform remove efficiency. By crushing a coating film using a jig 21 of the present invention, damage to a coated product can be suppressed and about uniform crushing of a coating film can be afforded in a short time as compared to scraping with conventional abrasive paper or grinder, removal by conventional sandblast method, removal by conventional striking of a coating film with a hammer and the like, because the coating film is crushed by pressing an abrasive against a coating film. In addition, the crushing of a coating film using a jig 21 of the present invention is free of deformation, swelling, dissolution, decomposition and the like of a coated product when removing the coating film, unlike the conventional chemical removal of a coating film using a strong peeling agent alone. By the use of the jig 21 for crushing a coating film of the present invention, therefore, a coating film can be removed easily with good workability, while suppressing damage to a coated product. The pieces of the coating film after crushing can be removed easily by suction and the like.

[0097] For crushing the coating film, jig 21 may be reciprocated manually by an operator holding a holding part to be mentioned below, or automatically reciprocated by the action of a motor or a vibrator installed. Particularly when a coated product is a floor material, irregularities and undulation of the surface of a coating film tend to have more complicated shapes. Thus, reciprocation in 4 directions or 8 directions is preferable rather than reciprocation in a constant direction, which affords more uniform crushing of the coating film.

[0098] The jig 21 for crushing a coating film of the present invention preferably comprises a press element 23 connected to a jig base 22 such that an angular displacement of an end 23 a thereof can be elastically achieved relative to the jig base 22. As used herein, the “angular displacement” of the end 23 a of the press element 23 means a displacement to change the angle of the end 23 a of the press element 23 about one optional point of the jig base 22. The structure to achieve such connection is not particularly limited, and conventionally known various systems can be employed to realize this connection.

[0099]FIG. 10(a) is a sectional view of the front view of jig 21 shown in FIG. 6 wherein section v is enlarged, and FIG. 10(b) is a sectional view wherein a tip 23 a of a press element 23 is displaced from the state shown in FIG. 10(a) relative to a jig base 22. The following is a preferable embodiment wherein the aforementioned connection is realized by a simple structure in view of FIG. 9.

[0100] In an embodiment shown in FIG. 9 and FIG. 10, the above-mentioned shafts 25 are inserted in through holes 24 in such a manner that they can reciprocate and capable of angular displacement at least in the through holes 24. By the above-mentioned shaft 25 being capable of angular displacement is meant that a shaft 25 in a through hole 24 is fixed at one point and an end thereof can deviate from the central axis of the through hole (shaft 25 having an inclination from a through hole 24). In an embodiment shown in FIG. 9 and FIG. 10, a clearance is formed in shaft 25, in other words, by making the size of the through hole 24 greater than that of the shaft 25, shaft 25 becomes reciprocatable and oscillatable in the through hole 24. Because a press element 23 is connected to jig base 22 via such shaft 25, the shaft 25 is capable of angular displacement in the through hole 24 in conjunction with the displacement of press element 23 comprising angular displacement of an end 23 a relative to the jig base 22, whereby a connection affording angular displacement of the end 23 a of a press element 23, in addition to the above-mentioned displacement to approach or leave the jig base 22. In an embodiment shown in FIG. 9 and FIG. 10, an elastic member 26 is present between a jig base 22 and a press element 23, as mentioned above. This elastic member 26 affords elastic angular displacement of the above-mentioned end 23 a of a press element 23.

[0101] Given the jig 21 for crushing a coating film permitting elastic angular displacement of the end 23 a of the press element 23 to the jig base, each end 23 a of a press element 23 can be inclined in accordance with the irregularities and slope of undulation of the surface of a coating film, thereby enabling press closely following the irregularities and undulation of the surface of a coating film.

[0102] In the present invention, the through hole of the jig base may not be necessarily parallel to each other as in the embodiment mentioned above. In the jig for crushing of the present invention, the above-mentioned through holes may or may not be in an about parallel relationship with each other. It is preferable that a gap should not be formed between press elements in the direction about perpendicular to the reciprocating direction, when the jig for crushing is reciprocated. In an embodiment shown in FIG. 6-FIG. 10, 10 press elements 23 are arranged in two rows containing 5 each in staggered intervals from each other. As a result, the press elements in one row are disposed in the gap between press elements in the other row, and the press elements adjacent in the same row can permit angular displacement of each other and the gap between press elements in the direction about perpendicular to the above-mentioned reciprocating direction is not formed. This ensures about uniform crushing of a coating film by the use of a jig for crushing.

[0103] As a means for elastically realizing the displacement to approach or leave the jig base and angular displacement of the press element, the above-mentioned embodiment comprises a press element 23 connected to a jig base 22 via a shaft 25 inserted in a through hole 24 and an elastic member 26 interposed between jig base 22 and press element 23. The above-mentioned means of the present invention is not limited to this. For example, jig base and press element may be directly connected with an elastic member.

[0104] The press element 23 of the present invention is not particularly limited as regards the shape thereof. The end 23 a is preferably a column having a curve forming a protrusion toward the direction away from the jig base 22, as shown in FIG. 6-FIG. 10. When the tip of the press element has an about planar surface, an abrasive cannot be pressed about uniformly against the surface of a coating film, possibly lowering the removal efficiency of a coating film. This tendency becomes particularly noticeable when the surface of a coating film has irregularities and undulation. When the tip of the press element is sharp, it may damage a coated product during transfer of the press element and cause poor workability. When the press element is a sphere, it easily follows when the surface of a coating film has irregularities and undulation. However, due to the small contact area, it unpreferably requires a long time to crush a certain area about uniformly. The press element 23 easily follows irregularities and undulation on the surface of a coating film and a great load can be applied. It preferably has an end 23 a which is a column having a curve forming a protrusion toward the direction away from the jig base 22. Particularly as shown in FIG. 6-FIG. 10, it is preferable that the press element be connected to the jig base 22 such that the axis of the columnar press element is in the direction about perpendicular to the reciprocating direction of the jig 21.

[0105] In the present invention, the size of the press element 23 is not particularly limited. For example, in the embodiment shown in FIG. 6-FIG. 10, when the length of the press element (length along the axis of column) X1 is 2 cm-4 cm, the entire jig 21 for crushing the coating film can press 20 cm-45 cm width X2 at once. Upon reciprocation of the jig, a coating film having certain width and area can be crushed.

[0106] In the present invention, the degree of displacement of the press element 23 is not particularly limited. The displacement to approach or leave the jig base 22 is preferably not less than 0.5 cm generally along the through hole 24, and the angular displacement relative to the jig base 22 is preferably expressed by the linear distance of about 0.5 cm between the ends 23 a before and after the displacement, when the above-mentioned length X1 of press element 23 is 3 cm.

[0107] The load to be applied to the press element 23 is not particularly limited and can be appropriately determined according to the thickness and physical properties of a coating film to be crushed. It is preferably about 5 kg-10 kg when the entire jig 21 can press the press element against 30 cm width X2 at once.

[0108] In the jig 21 of the present invention, when the press element 23 is connected to the jig base 22 via shaft 25 as shown in FIG. 9 and FIG. 10, the shaft 25 is preferably set engageably in the jig base 22, so that the press element 23 can achieve a predetermined displacement without falling off of the shaft 25 from the through hole 24, losing connection to the jig base 22. The mode of engageable setting of the shaft 25 in the jig base 22 is not particularly limited. In the embodiment shown in FIG. 6-FIG. 10, for example, the through hole 24 is formed to penetrate the planar jig base 22 generally in the thickness direction, and the shaft 25 can be engaged in the jig base 22 by forming an end 27 opposite from the connection to the press element 23 greater than the through hole 24.

[0109] The jig 21 for crushing a coating film of the present invention may additionally have a holding part to allow manual reciprocation by an operator. In the embodiment shown in FIG. 6-FIG. 8, a long and thin holding part 28 protrudes from the side opposite from the connection of the press element 23 to the jig base 22. Such holding part 28 leads to efficient operation in the site where a coating film is crushed, as compared to a jig without a holding part.

[0110] The jig 21 for crushing a coating film shown in FIG. 6-FIG. 10 only shows one preferable embodiment of the present invention, and the invention is not limited to this embodiment.

[0111] The abrasive to be used along with the jig for crushing a coating film of the present invention is exemplified by the abrasive powder and the abrasive paper shown with regard to the above-mentioned method of removing a coating film.

(EXAMPLES)

[0112] The method of removing a coating film of the present invention is explained in detail in the following by referring to Examples.

[0113] In this embodiment, various coating films were formed on a floor material and removed by various methods. The removal ratio of each coating film, damage to a coated product, degradation by swelling, dissolution, decomposition and the like were visually evaluated. In the preparation of coating solutions and peeling agents, “%” means “wt %” unless otherwise specified.

Example 1

[0114] An aqueous polyurethane resin (Neo Rez R972, solid content 34%; Avecia Limited) was diluted with tap water to a solid content of 20% to give a coating solution for a coating film.

[0115] This coating solution forms a coating film that can be dissolved in a peeling agent (FRONTIER Z, POMY CO., LTD.) for a vinyl floor diluted 2-fold with tap water.

[0116] The coating solution was applied to a vinyl floor tile as a coated product with a roller (AOZORA, Ohtsuka Brush Mfg. Co., Ltd.) so that the film thickness after curing would be 5 μm. The vinyl floor tile was INLAID ERDE (TAKIRON Co., LTD.). The tile was stood at room temperature for 1 hr to evaporate the solvent and cured, whereby a coating film soluble in a peeling agent was formed.

[0117] An aqueous UV curable resin (Laromer LR8895, solid content 50%) was diluted with tap water to a solid content of 30% and a photoinitiator (DAROCURE 1173, Ciba Specialty Chemicals K.K.) was added at 2% to give a coating solution. This was applied to a coating film soluble in the peeling agent formed above with the same roller as the above-mentioned so that the film thickness after curing would be 15 μm. The film was stood at room temperature for 1 hr to evaporate the solvent.

[0118] The film was exposed to the light of 420 mj/cm² from a high pressure mercury lamp (H05-L21; EYE GRAPHICS CO., LTD.), whereby a coating film 1 consisting of a surface aqueous UV curable resin layer and a lower layer soluble in a peeling agent was formed on the surface of a coated product 5 as shown in FIG. 1(a).

[0119] As shown in FIG. 1(b), an alumina abrasive powder 2 having a particle size of P120 was uniformly applied to the is surface of the coating film 1, and as shown in FIG. 1(c), the abrasive powder 2 was pressed against the coating film 1 with a press surface 77 of a press element 7. The press element 7 is an about rod shaped member having a length of 30 cm and a width of 10 cm, wherein a part of the side thereof is the press surface 77. The press surface 77 of the press element 7 is, as shown in FIG. 3, a curve evidently forming a curve in the direction of move.

[0120] As shown in FIG. 2(d), the press element 7 was reciprocated 40 times at a rate of 30 cm/sec on the abrasive powder 2, thereby pressing the abrasive powder 2 plural times against the surface of the coating film 1. As shown in FIG. 2(e), the coating film 1 was crushed to give a crushed coating film 15. Most of the crushed coating film 15 consisted of crushed pieces 10 of the coating film 1, leaving the coating film 1 in the lower layer. The remaining coating film 1 had a recess 11 along the shape of particulate abrasive powder 2 with crack 12 on the periphery.

[0121] As shown in FIG. 2(f), the abrasive powder 2 and crushed pieces 10 of the coating film 1 were removed by suction with a vacuum cleaner. At this stage, removal of part of the coating film 1 was visually confirmed.

[0122] Then as shown in FIG. 2(g), the above-mentioned peeling agent 3 for vinyl floor was applied to the surface the remaining coating film 1. Two hours later, the peeling agent 3 and the coating film 1 were washed away with water. The peeling agent 3 did not damage or dissolve the vinyl floor tile, which was a coated product.

[0123] As shown in Table 1, the removal ratio of the coating film was 100%, without degradation of the coated product. The surface of the coated product 5 was free of damage such as scratch and the like.

[0124] The peeling agent used in this embodiment does not, unlike the conventional agents, damage or dissolve a vinyl floor tile, which is a coated product. The peeling agent inherently shows relatively weak capability to dissolve a coating film. As shown in FIG. 2(f), the coating film 1 after pressing the abrasive powder 2 showed decreased thickness of the crushed pieces and cracks 12 in the surface, indicating the state where the peeling agent 3 can easily infiltrate into the inside of the coating film. This enabled complete and easy removal of the remaining coating film even with relatively weak peeling agent 3.

Example 2

[0125] The aqueous polyurethane resin used in Example 1 was diluted with tap water to a solid content of 20% to give a coating solution. This coating solution was applied to a vinyl floor tile as used in Example 1 with a roller similar to that used in Example 1 so that the film thickness after curing would be 5 μm. The tile was stood at room temperature for 1 hr to evaporate the solvent, whereby a layer soluble in a peeling agent was formed.

[0126] The organic solvent-based acrylic resin paint (KC-10, GEN GEN CORPORATION) was applied to a layer soluble in a peeling agent formed in the above with a roller in a similar manner, so that the film thickness after curing would be 15 μm. It was stood at room temperature for 24 hr to evaporate the solvent, whereby an acrylic resin paint layer was formed. By these steps, a coating film consisting of a surface acrylic resin paint layer and a lower layer soluble in a peeling agent, that are formed on the surface of a coated product, was obtained.

[0127] An abrasive paper (F sheet, particle size P120, KOVAX Corporation) comprising an alumina abrasive powder having a particle size of P120 attached to the surface thereof was press adhered to the coating film. A press element was applied thereon to press the abrasive paper against the coating film.

[0128] As shown in FIG. 4, the apparatus 70 equipped with a jig for crushing a coating film has a rotary seat 6 set on the bottom 72 of the polisher 71. The polisher is a machine to wash a floor surface by rotating a brush or a plastic scrubbing brush and used widely by building maintenance companies and cleaning companies. Those available from POMY CO., LTD., Zaoh Co., PENGUIN WAX CO., LTD., Konishi Co., Ltd. and the like are used. The apparatus 70 equipped with a jig for crushing a coating film in this embodiment utilizes this polisher 71. The polisher 71 has a control handle 75.

[0129] As shown in FIG. 5, the rotary seat 6 has a disc shape having a mount hole 61 in the center. The rotary seat 6 has four fixed casters 66 having a turning roller 65. The turning roller 65 is spherical and is attached to the caster 66 to secure smooth rotation in all directions. The lowermost part of the turning roller 65 is the press surface 67 to press an abrasive powder. The rotary seat 6 has an attachment 62 installed thereon. The drive disk 73 of the polisher 71 has a mount hole 61, by which it is fit into the attachment 62. The drive disk 73 rotates by the action of a motor set inside the polisher 71. The rotation of this drive disk 73 causes rotation of the rotary seat 6.

[0130] The rotary seat 6 is formed by processing a 18 mm thick veneer. The rotary seat 6 has a diameter of 30 cm. The caster 66 having a turning roller 65 is fixed to the rotary seat 6 with a fixing screw 661. The turning roller 65 has a diameter of 2.5 cm. The rotary seat 6 rotates at a rate of 200 rpm. The moving rate of the apparatus 70 equipped with a jig for crushing a coating film was 1 m² per 2 minutes.

[0131] By the aforementioned steps, the coating film was partly crushed into crushed pieces. The remaining coating film had a recess along the shape of the abrasive powder with cracks.

[0132] Then the abrasive paper was removed and the crushed pieces of the coating film were removed by suction with a vacuum cleaner.

[0133] Then the same peeling agent as used in Example 1 was applied to the surface of the remaining coating film.

[0134] As shown in Table 1, the removal ratio of the coating film was 100%. The coated product was free of flaws, deterioration or dissolution.

Comparative Example 1

[0135] A strong solvent-based peeling agent (100 g/m², SKELETON, NATOCO CO., LTD.) was applied to the surface of the vinyl floor tile having a coating film, as prepared in Example 1, and stood at room temperature for 2 hours. The surface was washed away with water. As shown in Table 1, the removal ratio of the coating film was 100%, but the surface of the coated product was dissolved.

Comparative Example 2

[0136] The peeling agent (FRONTIER Z) for a vinyl floor used in Example 1 was applied to the surface of the vinyl floor tile having a coating film, as prepared in Example 1, and stood for 2 hours. The surface was washed away with water.

[0137] As shown in Table 1, the surface of the coated product was not degraded, but the removal ratio of the coating film was 0%.

Comparative Example 3

[0138] The surface of the vinyl floor tile having a coating film, as prepared in Example 1 was ground with an abrasive paper (F sheet, particle size P120, KOVAX Corporation). As a result, ground pieces of the coating film were produced, partly leaving the coating film thereunder. The abrasive paper was removed and the ground pieces of the coating were removed by suction with a vacuum cleaner. The peeling agent (FRONTIER Z) for vinyl floor diluted 2-fold with tap water was applied to the surface of the remaining coating film. After leaving for 2 hours, the peeling agent was removed.

[0139] As shown in Table 1, the removal ratio of the coating film was 80%, leaving many grinding flaws on the surface of the coated product. TABLE 1 Ex. 1 Ex. 2 Com. Ex. 1 Com. Ex. 2 Com. Ex. 3 Removal 100% 100% 100% 0% 80% ratio Degradation none none dissolution none Many of coated of coated grinding product product flaws

[0140] As is evident from the foregoing explanation, according to the present invention, a coating film can be removed easily in a short time while suppressing damage to a coated product and degradation of the coated product. The present invention also provides a method of crushing a coating film by pressing an abrasive about uniformly even if the surface of a coating film has irregularities and undulation.

[0141] This application is based on a patent application Nos. 2001-159232 and 2000-382534 filed in Japan, the contents of which are hereby incorporated by reference. 

What is claimed is
 1. A method of removing a coating film from the surface of a coated product, which method comprises supplying an abrasive onto the surface of a coating film, pressing the abrasive against the surface of the coating film with a press surface of a press element to convert the coating film into a crushed coating film, and removing the abrasive and the crushed coating film.
 2. The method of claim 1, which further comprises applying a peeling agent onto a surface of the crushed coating film.
 3. The method of claim 2, wherein the peeling agent dissolves at least a lowermost layer of the coating film.
 4. The method of claim 1, wherein the press surface of the press element is curved.
 5. The method of claim 1, wherein the press element is a free turning roller.
 6. The method of claim 5, wherein the turning roller is attached to a rotary seat of a rotary driven type.
 7. The method of claim 1, wherein the press surface of a press element has a curve winding in the direction of movement.
 8. The method of claim 1, wherein the abrasive is pressed plural times against the surface of a coating film with a press surface of a press element.
 9. The method of claim 1, wherein the coated product is a floor material.
 10. A method of removing a coating film from the surface of a coated product by the use of a jig for pressing an abrasive onto a coating film with a press element to crush the coating film, wherein the jig comprises a jig base and plural press elements, and the press elements are connected to the jig base such that each press element can be at least displaced to elastically approach or leave the jig base.
 11. The method of claim 10, wherein said jig base has plural through holes, and each press element is connected to the jig base via plural shafts inserted into each through hole in such a manner that they can at least reciprocate in each through hole.
 12. The method of claim 10, wherein the press element is connected to the jig base such that the press element can be at least displaced to elastically approach or leave the jig base and an end thereof is capable of elastic angular displacement relative to the jig base.
 13. The method of claim 12, wherein said jig base has plural through holes, and each press element is connected to the jig base via plural shafts inserted into each through hole in such a manner that they are capable of reciprocation and angular displacement in each through hole.
 14. The method of claim 10, further comprising an elastic member between the jig base and the press element.
 15. The method of claim 10, wherein the press element is a column having a curved end forming a protrusion toward the direction away from the jig base. 